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Biomedical subjects

K I Kirk

Publications and source records attributed to K I Kirk.

15 recordsLinked to original sources
PubMed1996

Speech perception and speech production skills of children with multichannel cochlear implants.

The acquisition of speech perception and speech production skills emerges over a protracted time course in congenitally deaf children with multichannel cochlear implants (CI). Only through comprehensive, longitudinal studies can the full impact of cochlear implantation be assessed. In this study, the performance of CI users was examined longitudinally on a battery of speech perception measures and compared with subjects with profound hearing loss who used conventional hearing aids (HA). The average performance of the multichannel cochlear implant users gradually increased over time and continued to improve even after 5 years of CI use. Speech intelligibility was assessed from recordings of the subjects' elicited speech and played to panels of listeners. Intelligibility was scored in terms of percentage of words correctly understood. The average scores for subjects who had used their CI for 4 years or more exceeded 40%.

Child, Preschool↗
PubMed1995

Lexical effects on spoken word recognition by pediatric cochlear implant users.

OBJECTIVE: The purposes of this study were 1) to examine the effect of lexical characteristics on the spoken word recognition performance of children who use a multichannel cochlear implant (CI), and 2) to compare their performance on lexically controlled word lists with their performance on a traditional test of word recognition, the PB-K. DESIGN: In two different experiments, 14 to 19 pediatric CI users who demonstrated at least some open-set speech recognition served as subjects. Based on computational analyses, word lists were constructed to allow systematic examination of the effects of word frequency, lexical density (i.e., the number of phonemically similar words, or neighbors), and word length. The subjects' performance on these new tests and the PB-K also was compared. RESULTS: The percentage of words correctly identified was significantly higher for lexically "easy" words (high frequency words with few neighbors) than for "hard" words (low frequency words with many neighbors), but there was no lexical effect on phoneme recognition scores. Word recognition performance was consistently higher on the lexically controlled lists than on the PB-K. In addition, word recognition was better for multisyllabic than for momosyllabic stimuli. CONCLUSIONS: These results demonstrate that pediatric cochlear implant users are sensitive to the acoustic-phonetic similarities among words, that they organize words into similarity neighborhoods in long-term memory, and they use this structural information in recognizing isolated words. The results further suggest that the PB-K underestimates these subjects' spoken words recognition.

Age of Onset↗
PubMed1995

New directions for assessing speech perception in persons with sensory aids.

This study examined the influence of stimulus variability and lexical difficulty on the speech perception performance of adults who used either multichannel cochlear implants or conventional hearing aids. The effects of stimulus variability were examined by comparing word identification in single-talker versus multiple-talker conditions. Lexical effects were assessed by comparing recognition of "easy" words (ie, words that occur frequently and have few phonemically similar words, or neighbors) with "hard" words (ie, words with the opposite lexical characteristics). Word recognition performance was assessed in either closed- or open-set response formats. The results demonstrated that both stimulus variability and lexical difficulty influenced word recognition performance. Identification scores were poorer in the multiple-talker than in the single-talker conditions. Also, scores for lexically "easy" items were better than those for "hard" items. The effects of stimulus variability were not evident when a closed-set response format was employed.

Adult↗
PubMed1995

Speech perception skills of children with multichannel cochlear implants or hearing aids.

Perceptual skills were evaluated at two intervals of cochlear implant (CI) use in 24 children with prelingual deafness who received the Nucleus multichannel CI. Their performance was compared to that of age-matched children with prelingual profound hearing losses who used conventional hearing aids (HAs). The HA subjects were grouped by unaided thresholds: "gold" subjects (pure tone average of 92 dB hearing level) and "silver" subjects (pure tone average of 104 dB hearing level). The CI users' perceptual abilities increased significantly with time. At the "early" interval (mean, 2 months of CI use), performance of the CI and silver HA groups was similar on measures of phoneme, word, and sentence recognition; the gold HA subjects' performance was superior to that of the other groups. At the "late" interval, (mean, 2.5 years of CI use), CI subjects' performance exceeded that of the silver group on all measures, and was similar to that of the gold group on vowel recognition and auditory-plus-visual sentence recognition measures.

Audiometry, Pure-Tone↗
PubMed1995

Speech intelligibility of implanted children.

The speech intelligibility of 61 prelingually deaf children was measured prior to their receiving a multichannel cochlear implant (CI) and at subsequent intervals. The speech intelligibility of the implanted subjects was compared to that of three groups of subjects with profound hearing loss who used conventional hearing aids (HAs), grouped on the basis of unaided thresholds: "gold" (pure tone average [PTA] = 93 dB hearing level [HL]), "silver" (PTA = 103 dB HL), and "bronze" (PTA > or = 110 dB HL). Intelligibility was measured in terms of the percentage of words from a set of 10 sentences that were correctly understood by a panel of listeners. The speech intelligibility of the implanted subjects increased gradually over time, remaining relatively low throughout the first 2 years of implant use. After that time, the average speech intelligibility of the CI subjects surpassed that of the silver HA users. The gold HA subjects demonstrated speech intelligibility that was markedly better than that of the CI subjects, even after 3 1/2 or more years of implant use.

Child, Preschool↗
PubMed1995

Comparison of multichannel tactile aids and multichannel cochlear implants in children with profound hearing impairments.

Speech perception skills of prelingually deafened children who used the multichannel Tactaid 7 (n = 10) were compared to those of a matched group of children who used the Nucleus 22 channel cochlear implant (n = 10). Group scores were compared on a closed-set test of word recognition and on an open-set test of phrase recognition in the pre-device condition and at a post-device interval after an average of 1.5 years of multichannel device use. The results revealed that the scores of the implant users improved significantly between the pre- and post-device intervals on all measures. Moreover, the scores of the implant users were significantly higher than those of the tactile aid users on all measures. In contrast, the scores of the tactile aid users showed negligible change over time, except on a test that evaluated open-set recognition of phrases with both auditory and visual cues. The results suggest that children can learn to recognize words and understand speech without lipreading with a multichannel implant, whereas children who used the multichannel tactile aid demonstrate limited speech recognition skills only if auditory/tactile cues are combined with lipreading.

Child↗
PubMed1994

Single-channel to multichannel conversions in pediatric cochlear implant recipients.

Speech perception skills were measured in five children who had received a 3M/House single-channel cochlear implant and were subsequently upgraded to a multichannel cochlear implant (Nucleus). A rationale was developed based upon performance with the single-channel device and anticipated performance with the multichannel device. All subjects demonstrated improved acoustic thresholds with the multichannel device. Three of the children demonstrated improvements on identification tasks and two on word recognition tasks.

Adolescent↗
PubMed1993

Vowel and diphthong production by young users of cochlear implants and the relationship between the phonetic level evaluation and spontaneous speech.

This investigation assessed how the vowel and diphthong production of young users of cochlear implants varied over time and how performance on the Phonetic Level Evaluation (PLE, Ling, 1976) corresponded with vowel and diphthong production during spontaneous speech. Eight children with prelingual deafness were tested with the PLE on five occasions: before receiving a Cochlear Corporation Nucleus cochlear implant and at the following points after receiving a cochlear implant: 6 months, 12 months, 18 months, and 24 or 36 months. An audiovideo recording of spontaneous speech was obtained at each test session. Performance on the PLE was scored with the scoring system designed by Kirk and Hill-Brown (1985). Performance during spontaneous speaking was scored by referencing a transcription of the spoken message to a transcription of the signed message. The correlations between the PLE and the spontaneous speech measures were weak, suggesting that performance on the PLE has low predictive value for vowel and diphthong production during spontaneous speaking. The results from the spontaneous speech samples collected over time suggest that two changes occurred: (a) vowel and diphthong production became more diverse and (b) production became more accurate. It is suggested that increased access to formant information enables subjects to enlarge their system of phonological performance and refine their motoric ability to establish vowel and diphthong targets.

Child↗
PubMed1992

The use of static and dynamic vowel cues by multichannel cochlear implant users.

Multichannel cochlear implant users vary greatly in their word-recognition abilities. This study examined whether their word recognition was related to the use of either highly dynamic or relatively steady-state vowel cues contained in /bVb/ and /wVb/ syllables. Nine conditions were created containing different combinations of formant transition, steady-state, and duration cues. Because processor strategies differ, the ability to perceive static and dynamic information may depend on the type of cochlear implant used. Ten Nucleus and ten Ineraid subjects participated, along with 12 normal-hearing control subjects. Vowel identification did not differ between implanted groups, but both were significantly poorer at identifying vowels than the normal-hearing group. Vowel identification was best when at least two kinds of cues were available. Using only one type of cue, performance was better with excised vowels containing steady-state formants than in "vowelless" syllables, where the center vocalic portion was deleted and transitions were joined. In the latter syllable type, Nucleus subjects identified vowels significantly better when /b/ was the initial consonant; the other two groups were not affected by specific consonantal context. Cochlear implant subjects' word-recognition was positively correlated with the use of dynamic vowel cues, but not with steady-state cues.

Adult↗
PubMedDate not supplied

Cochlear implants in children.

In recent years, the House single-electrode cochlear implant has proven to be a clinically feasible prosthesis for profoundly deaf adults. Based on these findings, the decision was made to begin implanting those children who could not benefit from hearing aids. As of August 1982, 23 profoundly deaf children (ranging in age from 3.4 to 17.5 yrs) have received the cochlear implant. The majority were deafened by meningitis. Results to date indicate that children demonstrate sound field thresholds and receive timing/intensity information comparable to that of adult implant patients. Results have been extremely encouraging, but only long-term experience will determine the ultimate benefit of the implant in children.

Adolescent↗
PubMedDate not supplied

Speech and language results in children with a cochlear implant.

At the House Ear Institute, speech and language assessments are a regular part of the evaluation protocol for the cochlear implant clinical trials in children. The assessments are conducted preimplant and at specific postimplant intervals. Paired comparisons of the children's performance at pre- and post-implant intervals reveal significant improvements in both imitative and spontaneous speech production abilities. However, some differences between groups are noted. Children implanted at an early age demonstrate a greater number of significant improvements in speech production, while children using oral communication have better skills at all test intervals. In addition, significant improvements on three of the four receptive language measures and one of the four expressive language measures are demonstrated at the 6-mo postimplant test interval. A significant decrease in performance is noted for one receptive language measure. In a second study, the speech scores of control groups and postimplant groups of the same age (3, 4, or 5 yr) are compared. Implanted children score higher in all but one of 24 contrasts, and these differences are statistically significant in five of the comparisons.

Adolescent↗